Fit parchment into an 8x8 cake pan, leaving 1-2 inches extending above every side. The overhanging paper should form sturdy handles for lifting the chilled dessert.

Beat the cold heavy whipping cream in a large bowl with an electric mixer, then refrigerate it until needed. Stop when the cream looks fluffy and a lifted beater leaves an upright peak.

Stir the coffee with 1 tablespoon vanilla extract, 1/2 teaspoon espresso powder, and 2 tablespoons powdered monk fruit sweetener in a shallow bowl. The dipping mixture should look evenly blended, without visible pockets of powder.

Blend the softened mascarpone and cream cheese in a separate large bowl with a hand or stand mixer on medium speed for 1-2 minutes, then briefly incorporate the remaining 1 cup powdered sweetener. The cheese mixture should become uniform without prolonged beating after the sweetener disappears.

Mix 2 tablespoons of the prepared coffee mixture, 1 teaspoon vanilla extract, and 1 teaspoon espresso powder into the sweetened cheeses, reserving the rest of the coffee mixture for dipping. The filling should have an even coffee color with no streaks of extract.

Use a rubber spatula to gently lift and turn the whipped cream through the cheese mixture. Finish when the filling looks evenly blended and airy, with no separate white streaks.

Briefly dip each ladyfinger or sponge piece in the coffee mixture and cover the pan bottom, spread half the filling over it, then repeat with another dipped sponge layer and the remaining filling. The sponge should stay intact, and the cream should cover each tier evenly from edge to edge.

Sift the unsweetened cocoa over the leveled filling using a fine-mesh strainer. A thin, even coating should cover the surface without concentrated clumps.

Refrigerate the assembled dessert for 4-5 hours, preferably overnight. The filling should firm up as the coffee flavor settles into the sponge.

Scoop portions directly from the pan, or gently lift the chilled dessert by its parchment handles and cut it into squares. The layers should hold together while remaining tender enough to cut without force.